1. Field of the Invention
The present invention relates to a display, and more particularly, to a liquid crystal display (LCD).
2. Discussion of the Background
Liquid crystal displays (LCDs) are one of the most widely used types of flat panel displays. Generally, an LCD includes a pair of display panels having electric field generating electrodes, such as pixel electrodes and common electrodes, and a liquid crystal layer interposed between the display panels. In an LCD, voltages are applied to electric field generating electrodes to generate an electric field. Accordingly, the alignment of liquid crystal molecules of a liquid crystal layer is determined, and polarization of incident light is controlled. As a result, a desired image is displayed on the LCD.
In a vertical alignment (VA) mode LCD, liquid crystal molecules are arranged with the long axes of the molecules being perpendicular to the upper and lower display panels when no electric field is applied to the liquid crystal molecules. VA mode LCDs are popular due to their high contrast ratios and wide standard viewing angles. The standard viewing angle denotes a viewing angle with a contrast ratio of 1:10 or a critical angle of luminance conversion between grayscales.
In order to widen a standard viewing angle of a VA mode LCD, cutouts may be formed in electric field generating electrodes or protrusions may be formed on the electric field generating electrodes. The cutouts or protrusions can determine the directions in which the liquid crystal molecules tilt. By using cutouts or protrusions to control the orientation of the liquid crystal molecules, the standard viewing angle of the VA mode LCD can be increased.
However, a drawback of the VA mode LCD is that it may have poor lateral visibility compared to frontal visibility. For example, in a patterned vertical alignment (PVA) mode LCD having cutouts, images are brighter near the sides of the screen than in the center of the screen. In extreme cases, the luminance difference between high grayscales may disappear, causing the images to become very dull.
To overcome this drawback, each pixel may be partitioned into two subpixels, and a switching device is formed in each subpixel. Then, a different voltage is applied to each subpixel. In other words, different data voltages are applied to a pair of subpixels so that a pixel composed of the subpixels can express the desired luminance. In particular, if an LCD operates at a low gray voltage, it is actually driven by a subpixel to which a relatively high data voltage is applied. Therefore, coupling capacitances between a subpixel, to which a relatively high voltage is applied, and a pair of data lines on opposite sides of the subpixel should be matched in order to enhance display quality of the LCD.